Although many different recording formats are known for use in digital video tape systems which include record and/or replay units, each such system is designed to utilize only one format. Therefore, no compatibility exists between systems having different recording formats because a tape recorded by one system cannot be replayed in another system. If high quality performance is to be attained, a recording format requiring extensive tape consumption and complex signal processing circuitry must be utilized, which then becomes very cumbersome in portable recording equipment. However, simplification of recording format to gain enhanced compactness in portable record equipment by reducing tape consumption and the amount of circuitry, results in reduced performance.
It has been proposed to use a hierarchy of digital television standards wherein a higher data rate system would be available to attain the high quality performance required for studio equipment, and a lower data rate system would be available to attain compactness in portable equipment. One such hierarchy for the Y, I and Q components of a television signal provides for the higher data rate system by sampling the components in the ratio of 4:2:2 respectively, and provides for the lower data rate system by sampling the components in the ratio of 2:1:1 respectively. For example, one currently contemplated standard utilizes a sampling frequency of 13.5 MHz corresponding to the level of 4 in the hierarchy, and therefore the levels of 2 and 1 would represent frequencies of 6.75 and 3.375 MHz, respectively. Although such hierarchies do provide for greater flexibility between studio and portable recording equipment, the individual recording formats for higher and lower data rate systems are not readily interchangeable in that a tape recorded by one system cannot be replayed directly in the other system. To convert the recording format of one system to the recording format of the other system, recorded information sampled at one hierarchy level must be replayed, transcoded into the other hierarchy level and re-recorded or otherwise transmitted around the studio.